Intravenous cannula assembly unit



June 18, 1968 D. R. Bowes INTRAVENOUS CANNULA ASSEMBLY UNIT Filed March22, 1966 /Vw///n//V /Yv NN E INVENTOR. aA/Az en/Es ATTORNE I UnitedStates Patent O 3,388,703 INTRAVENGUS CANNULA ASSEMBLY UNIT Donald R.Bowes, Fanwood, NJ., assignor to Johnson It Johnson, a corporation ofNew Jersey Filed Mar. 22, 1966, Ser. No. 536,376 7 Claims. (Cl.12S-214.4)

ABSTRACT F THE DISCLOSURE An intravenous cannula assembly unitcomprising a rigid hypodermic needle and a ilexible cannula fitted overthe needle and shrunk into intimate contact with the shank of the needleand in particular, with a reduced diameter portion of the needle locatedbetween the head and the shank of the needle. As a result, the combinedneedlecannula diameter just rearwardly of the needle point is no greaterthan the normal diameter of the needle Shank, thereby reducing thelikelihood of trauma in inserting the unit.

The present invention relates to intravenous devices of the type whichare inserted in a vein or body cavity to allow fluids to be infused intoor removed from the patient.

Devies of this type are described in United States Letters Patent3,030,953 and 3,094,122 and generally are in the form of an insertionunit comprising a rigid hypodermic needle and a flexible cannula fittedover the needle. The unit normaly is fitted on the end of a hypodermicsyringe for insertion into the vein and then the syringe and needle areremoved from the cannula after the cannula has been properly positionedlfor use. The cannula then is attached through suitable 4fittings totubing through which the desired uid may be administered or removed.

In using this type of unit, it is sometimes diiiicult to control thepain of insertion due to the large diameter of the needle-cannulacombination. Efforts have been made to recess the leading end of thecannula behind an enlarged shoulder adjacent the point of the needle.However, this does not solve the problem created by the increaseddiameter of the unit, and creates an additional problem in withdrawingthe needle through the cannula.

The present invention contemplates an intravenous device of the abovegeneral type wherein the combined needle-cannula diameter of the portioninserted prior to removal of the needle is no greater than normal needlediameter and wherein, in fact, the front portion of the cannula does notprotrude at all beyond the needle head. For this purpose, the needlecomprises a needle head of normal needle diameter adjoining the pointedfront end of the needle, a shank of normal needle diameter adjoining therear end of the needle, and an elongated section of reduced diameterbetween the head and the shank of the needle. A flexible hollow plasticcannula then is placed over the needle and shrunk into intimate contactwith the outer surfaces of the reduced section and shank thereof. Thisprovides a reduced diameter -portion at the tip of the cannula justrearwardly ofthe needle head and assures that the tip of the cannulagrips the needle securely so that there will be no undesired relativemovement between the cannula and the needle at any time. The reducedsection of the needle is connected to the head of the needle and theshank, respectively, by smoothly tapered front and rear annular fairingsurfaces which provide a gradual transition between the normal needlediameter of the head and the shank and the reduced diameter sectionbetween them. The difference between the outer diameters of the needlehead and the reduced section just rearwardly of the head issubstantially equal to the thickness of the hollow cannula wall, withthe result that the outer diameter "ice of the reduced diameter tipportion of the cannula which is shrunk over the reduced section of theneedle is substantially equal to the outer diameter of the needle head.

Preferably, the front end of the cannula wall, at the tip of thecannula, fits over the front fairing surface of the needle and istapered to conform generally to the taper of the front fairing surface.This imparts maximum flexibility to the front end of the cannula walland thereby facilitates fleXure of the cannula over the needle head whenthe needle is withdrawn through the cannula. The tapering of the cannulawall in this manner also allows the cannula to extend out to the surfaceof the head of the needle without protruding radially beyond the needlehead. The front end of the cannula wall may be tapered for this purposeeither before or after it is shrunk in position over the needle.Preferably, however, it first is shrunk in the desired position and thenground or cut down at the tip to reduce the outer diameter of the tip ofthe cannula to that of the needle head and thereby provide the aforesaidtapered section at the tip of the cannula.

The reduced section of the needle should be at least twice as long asthe needle head and, at any rate, of sufticient length to assure thatthe reduced portion of the cannula can be properly positioned in theappropriate vessel or body cavity prior to removal of the needle throughthe cannula. `In other words, one of the main advantages of thisinvention is that the needle-cannula combination may be inserted easilyuntil the reduced portion of the cannula, which is shrunk into contactwith the reduced section of the needle, has been inserted into thevessel, and then the needle may be removed -by withdrawing it throughthe cannula. Thereafter, the cannula may be inserted further into thevessel with minimum trauma because the rigid needle has been removedtherefrom and the cannula itself is flexible both radially andlaterally.

Preferably, the needle is hollow and the reduced section thereof isformed by applying pressure to the needle as it is being rotated incontact with a suitable tool thereby simultaneously reducing its innerand outer diameter. The tool used may be appropriately shaped to assurethat the front and rear fairing surfaces are formed in the desiredshape. This technique is very simple and quick. However, during thisstep, the lumen of the needle normally should not be reduced to adiameter of less than about 0.01 inch.

Other and further advantages of this invention will occur to one skilledin the art from the following description and claims taken together withthe drawings wherein:

FIG. 1 is a plan view of an intravenous device according to a preferredembodiment of this invention, mounted on the front end of a hypodermicsyringe.

FIG. 2 is an exploded view of the cannula, needle and syringe of theembodiment of FIG. 1 in unassembled relation to one another.

FIG. 3 is a greatly enlarged view partly in section and partly inelevation of the front end of the device of FIG. 1, showing the cannulabefore its wall has been tapered at the tip of the cannula.

FIG. 4 is a view partly in section and partly in elevation and similarto FIG. 3 showing the tip of the cannula after it has beenl tapered.

FIG. 5 is a very greatly enlarged view showing how the tip of thecannula fits against the adjacent portions of the needle.

FIG. 6 is an enlarged sectional view taken along the line 6--6 of FIG.4.

FIG. 7 is a view partly in section and partly in elevation at the sameenlargement as FIGS. 3 and 4, and showing the intravenous device of thepreceding figures after it has been inserted through the skin into avein in such a way that the reduced diameter portion of the device ispositioned in the vein and the needle is ready for removal from thedevice by withdrawing it through the cannula as indicated in phantom.

FIG. 8 is a partial section at the same enlargement as FIG. 7 showingthe tip of the cannula in position in the vein after the needle has beenremoved therefrom. Referring to the drawings, there is shown anintravenous device, or unit, according to a preferred embodiment of thisinvention which comprises a rigid hollow pointed hypodermic needle 11and a fiexible hollow plastic cannula 12 fitted tightly over the needle.The needle 11 and cannula 12 are aihxed at their rear ends to first andsecond hubs, 13 and 14 respectively, by which they are assembled overone another and positioned on the front end of a hypodermic syringe 15for insertion of the unit into a patients vein 16 or body cavity.

The rear end of the needle 11 is permanently secured to the rst hub 13by conventional means, and this hub presents a rearwardly facing taperedsocket, not shown, and a frontwardly extending tapered extension 16awhich cncloses the needle.'The tapered socket is adapted to fit tightlyover a tapered fitting 17a at the front end of the syringe forpositioning the needle on the syringe, and the frontwardly extendingtapered extension 16a is adapted to fit inside a corresponding taperedsocket presented by the rear end f the second hub 14 which, in turn, isaffixed to the cannula 12. The cannula may be secured to the front endof the second hub 14 by conventional means such as are described inUnited States Letters Patent 3,094,122.

The hollow needle 11 possesses a normal outer diameter, i.e., is notenlarged, and is uniform in diameter throughout its length except for anelongated reduced diameter section 17 just rearwardly of the needlepoint. More specifically, the needle comprises a needle head 18 ofnormal needle diameter adjoining the pointed front end of the needle anda shank 19 of normal needle diameter adjoining the rear end of theneedle. The reduced diameter section 17 of the needle is located betweenthe head 18 and the shank 19 and is somewhat elongated as compared withthe diameter of the needle. The elongated reduced diameter section 17 isconnected to the head 18 of the needle by a smoothly tapered frontannular fairing surface 21 and is connected to the shank 19 of theneedle by a similar smoothly tapered rear annular fairing surface 22.The front and rear airing surfaces 21 and 22 provide gradual transitionbetween the normal needle diameter of the head 18 and the shank 19 andthe reduced diameter of the elongated section 17 between them. Thisreduced diameter section 17 of the needle is formed by turning hteneedle in contact with a fitting, not shown,

which presses the walls of the needle inwardly to reduce its outerdiameter to the desired extent without reducing the inner diameter ofthe needle below about 0.01 inch. This technique requires no specialmachining and is quick and efrlcient.

The hollow plastic cannula 12 is placed over the needle 11 in 1such away that its front end or tip 23 overlaps the front fairing surface 21of the needle but not the outer surface of the needle head 18. Thecannula 12 then is shrunk into intimate contact with the outer surfacesof the reduced section 17 and the shank 19 of the needle. This shrinkingmay be accomplished by heat or by swelling the plastic of the cannula 12prior ot fitting the cannula over the needle 11 and then drying it tocause it to shrink tightly over the needle. The cannula may be formedfrom any suitable material such as polyvinyl chloride or polyethylenewhich may be shrunk in this manner and is otherwise non-toxic andsuitable for this use.

The wall of the cannula 12 at its front end or tip 23 is tapered so thatit conforms with the taper of the front fairing surface 21 of the needleand does not extend radially beyond the outer diameter of the head 18 ofthe needle as is clearly shown in FIGS. 4, and 7. This may beaccompanied by tapering the front end of the cannula wall prior toshrinking it in place over the needle or by rst shrinking a cannula 12having uniform wall thickness onto the needle, as shown in FIG. 3. Inthe latter case, the tip 23 of the cannula initially will protruderadially outwardly beyond the head 1S of the needle. The cannula then istapered as shown in FIG. 4 by grinding or cutting down the front endofthe cannula wall to the same outer diameter as the needle head 18.

The difference between the outer diameter of the needle head 18 and thereduced section 17 ofthe needle just rearwardly of the needle head issubstantially equal to the thickness of the hollow cannula wall. As aresult, the outer diameter of the reduced diameter tip portion 24 0f thecannula which is yshrunk over the Ireduced section 17 of the needle issubstantially equally to the outer diameter of the needle head 18. Thetapered front end 23 of the cannula wall allows the cannula 12 to extendout to the surface of the needle head 18 without protruding radiallybeyond the head. As a result, the intravenous device of this inventionpresents a substantially continuous cylindrical outer surface of uniformdiameter from the point `of the needle 11 to the rear end of the reduceddiameter section 17 of the device. This allows the unit to be insertedthrough the skin into the vein 16 as shown in FIG. 7 until the reduceddiameter portion 24 of the device is in position in the vein, withoutcreating an enlarged incision .or in any way increasing trauma due toinsertion of the front of the cannula into the vein or body cavity.Then, the rigid needle 11 may be removed easily from the cannula 12,while leaving the cannula in position in the vein, as shown in FIGS. 7and 8, merely by withdrawing the needle rearwardly through the cannula.During this rearward motion of the needle, the tapered front end 23 ofthe cannula flexes outwardly and slides easily over the tapered frontfairing sur-face 21 of the needle 11 so that a -minimum of resistance ispresented to the withdrawal of the needle, thereby minimizing any traumawhich might occur at this point. After the rigid needle 11 has beenwithdrawn yfrom the cannula, the front end 23 of the cannula remains inposition in the vein, as shown in FIG. 8. Since the material of thecannula is quite flexible, the cannula itself now has become flexible inboth a radial and a lateral direction. Thus, the cannula may be insertedfurther into the vessel with minimum trauma, if further insertion isdeemed necessary for any reason. When the cannula 12 has reached thedesired position, its hub 14 may be affixed to the skin by tape .orother means and attached to a tube, not shown, so that the cannula maybe used for removal of blood from the vein or infusion of the desiredfluid into the body.

Having now described the invention in specific detail and exemplifiedthe manner in which it may be carried into practice, it will be readilyapparent to those skilled in the art that innumerable variations,applications, modifications, and extensions of the basic principlesinvolved may be made without departing from its spirit or scope.

What is claimed is:

1. An intravenous device which comprises a rigid needle comprising asharp pointed front end, a needle head of normal outer diameteradjoining the pointedy front end of the needle, a shank of normal outerdiameter adjoining the rear end of the needle, and an elongated sectionyof reduced diameter between the head and the shank of the needle; and aflexible hollow plastic cannula surrounding said needle and shrunk intointimate contact with the outer surfaces of the reduced section and theshank of said needle and providing a reduced diameter portion of thecannula just rearwardly of the needle head, the thickness of the cannulawall being substantially equal to the difference between the normalouter diameter of the needle and the outer diameter of said reducedsection with the result that the outer diameter of the reduced 4diametercannula portion shrunk over the reduced section of the needle issubstantially equal to the outer diameter of the needle head and thefront end of said cannula does not protrude radially beyond said head,the rear end of the needle being attached to a needle fitting whichallows the needle to be mountedfon a hypodermic syringe or otherwisemanipulated for insertion of the device into a blood vessel or bodycavity and the rear end Iof the cannula being attached to a cannulafitting which is adapted to be connected with tubing for infusing fluidinto or removing it from the said vessel or cavity, and said cannulabeing adapted to ex and slide over the needle head when the needle isremoved from the cannula by withdrawing it through the cannula after thereduced diameter portion o fthe device is properly positioned in thesaid vessel or cavity.

2. An intravenous device according to claim 1, wherein the outer surfaceof the reduced section of the needle is connected to the larger diameterouter surfaces of the head and the shank, respectively, by smoothlytapered front and rear annular fairing surfaces.

3. An intravenous device according to claim 2, wherein the front end ofthe cannula wall fits over the front fairing surface of the needle andis tapered to conform generally to the taper of the front fairingsurface so that the yfront end of the cannula does not protrude radiallyoutwardly beyond the adjacent needle head, thereby imparting maximumflexibility to the front end `of the cannula and facilitating liexure ofthe cannula over the head when the needle is Withdrawn through thecannula.

4. An intravenous device according to claim 3, wherein the wall of saidcannula is uniform in thickness when fitted tonto said needle, andwherein the front end of the cannula is ground or cut down to reduce itsouter diameter to that of the needle head and provide the aforesaidtapered section at the front end of the cannula.

5. An intravenous device according to claim 1, wherein the reducedsection of the needle is at least twice as long as the needle head toassure that the reduced diameter portion of the cannula can be properlypositioned in the said vessel or body cavity prior to removal of theneedle through the cannula.

6. An intravenous device accor-ding to claim 1, Wherein the needle ishollow and the reduced section of the needle is formed by applyingpressure to the needle as it is being rotated, thereby simultaneouslyreducing its inner and outer diameter.

7. An intravenous device according to claim 6, wherein the lumen of theneedle in said reduced section has a diameter of no less than about 0.01inch.

References Cited UNITED STATES PATENTS 2,770,236 11/1956` Utley et al.12S-221 2,899,960 8/ 1959 Ginsburg 128-221 3,030,953 4/ 1962 Koehn128-214.4 3,082,769 3/ 1963 Palmer 12S- 221 3,094,122 6/ 1963 Gauthieret al. 12S-214.4 3,352,306 11/1967 Hirsch 12S- 214.4

DALTON L. TRULUCK, Primary Examiner.

UNITED STATES PATENT oEEIcE CERTIFICATE OF CORRECTION Patent No.3,388,703 June 18, 1968 Donald R. Bowes It is certified that errorappears in the above identified patent and that said Letters Patent grehereby corrected as shown below:

Column 1 line 27 "Deves" should read Devices Column 3, line 49, "hte"should read the Column 4,

equal line 64, "shrunk line 13, "equa11y should read into" should readhavngits inner surfaces in Signed and sealed this 28th day of October1969.

(SEAL) Attest:

, Edward M. Fletcher, Ir.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, IR.

